One page site menu bar

I am building a one page site and after reading the documents – I still have a question. How do I make a menu bar item that brings the reader all the way back to the top – when the top is a featured image?

I am also confused as to whether I need to be using the “one page” element or the “full width element”? Are they the same thing?

Final question – can I still attach a blog on a subpage? Will the one page menu still work if a sub page menu is added?
Thanks for your help.
Margie
http://www.BlogFaceDesigns.com